Recently, a monitor apparatus, a television receiver and the like using a liquid crystal display panel are becoming more and more popular. Especially, in recent years, a size of a display screen of a liquid crystal display apparatus is increased and some of which are used for a purpose of advertisement display by, for example, setting a large-screen display on a street or the like. In such a liquid crystal display apparatus, since liquid crystal itself does not emit light, a backlight using, for example, an LED (Light Emitting Diode) is arranged on a back side of a liquid crystal display panel so that with irradiated light thereof, display with high luminance is performed.
In a color type display apparatus represented by a liquid crystal display apparatus using a liquid crystal display panel, adjustment of white balance is important. In adjustment of white balance, for example, input RGB signals are not directly output to a display but output after performing correction (γ correction) to each of the RGB signals so that especially white color is appropriately expressed.
However, there is a problem that light emission luminance of a backlight of a liquid crystal apparatus is changed due to switching between light modulation levels of the backlight or an elapsed time after powered on, so that white balance varies to cause reduction in video image quality.
Concerning a technology for appropriately performing white balance adjustment to display a video image with high display quality, for example, Japanese Laid-Open Patent Publication No. 2010-128040 discloses a display apparatus provided with correction means to perform γ correction to an input video image and detection means to detect luminance of a backlight, in which different γ correction is performed for each of RGB with the correction means according to a luminance level detected by the detection means.
As described above, detecting luminance of a backlight emitting light and adjusting white balance using a detected result is a useful technique. However, when light emission luminance of a backlight is detected for using in adjustment of white balance, when the backlight is turned on for adjustment of white balance, light from the backlight is transmitted through the liquid crystal display panel to be emitted to a front side depending on a state of a liquid crystal display panel. That is, on the liquid crystal display panel, in displaying an input video image signal, an oriented state of liquid crystal is changed according to gradation of the input video image signal, and gradation expression is performed by a function of an optical shutter. At this time, a transmitted light amount of the liquid crystal display panel is changed depending on a state of an optical shutter so that an amount of light incident on a detection sensor for detecting light emission luminance of the backlight does not become stable, thus resulting in reduction in detection accuracy.